goldsmith



(No Model.)

E. M. GOLDSMITH & E. REIZENSTEIN.

DEVICE FOR LAYING OFF GEOMETRIG FIGURES. No. 332,148. Patented Dec. 8, 1885.

Wiz'meoozaz tJiRS. Pmwmm w. Washinglnn. n. c.

NITE' STATES PATENT Orricn.

EDWIN M. GOLDSMITH AND EMILE REIZENSTEIN, OF PHILADELPHIA, PA.

DEVICE FOR LAYING OFF GEOMETRIC FIGURES.

SPECIFICATION forming part of Letters Patent No. 332,148, dated December 8, 1885.

Application filed June 19, 1885.

To all whom it may concern.-

Be it known that we, EDWIN M. GOLD- SMITH and EMILE REIZENSTEIN, both citizens of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvemerit in Devices for Laying off Geometric Figures, which improvement is fully set forth in the following specification and accompanying drawing, in which the figure is a face view of the device embodying our invention, the same consisting of a protractor-rim having connected with it triangular and other figures, the inner circumference of the rim being formed of right lines and segments, and other features are provided whereby various geometric figures may be laid off.

Referring to the drawings, A represents a disk having a rim, A, suitably graduated and adapted to be used as a protractor. Within the disk is a series of openings bounded by right lines and segments of different dimensions for laying off polygonal figures, sectors, chords, segments, 8:0. The disk is divided by a portion of these openings into figures B and G, from the former of which a right-angled triangle may be drawn, and from the latter a scalene triangle. The cross-bar D is also formed by the outlines of a portion of the openings. These several parts are connected to each other and to the rim, as is seen in the drawing. The base of the figure B joins the crossbar D, and between the same is a slot, E, which coincides with the side or edge F of the bar D, each being aradius, and together forming the diameter of a circle, the center being perforated, as at G, to receive a pin on which the disk may be rotated.

In the cross-bar D are scroll-shaped slots H, which extend from near the center of the disk outwardly toward the circumference, and in the figure Bis the slot J, having two of its sides extending radially, while the base or larger portion thereof is bounded by a curved line.

In the figure B and cross-bar D are rows of perforations a, which are arranged in radial lines, one row being adapted to receive the point of a lead-pencil and the other that of a 50 pin, so that by rotating the disk circles of different diameters may be drawn; but circles Serial No. 169,150. (No model.)

may be drawn from the center, G, the pencilpoiut being inserted in either of the perforations to, or at the corners of the figures B 0, bar D, or slots H J. It will be seen that when the disk is placed on a piece of paper, a slate, 810., on which it is desired to mark ofi' geometric figures, such figures may be drawn off by guiding the pencil along the sides of the several parts as formed, then turning the disk, marking off another section or part of a figure, and so continuously to the end. Thus the base of the scalene triangle formed by the figure 0 is the side of a square; hence after one side is drawn the other sides may be formed by turning the disk the requisite number of times, each time marking off another side. The side 6 of the bar D may be used for forming a triangle, and also the chord of an arc. The hypotenuse of the. right-angled triangle formed by the figure B may be used to describe and mark off a pentagon. The right lines of the rim A are employed for polygons, those shown being for six, eight, ten, twelve, and sixteen sides. Segments, sectors, chords, 850., may be described and drawn by using the proper part of the figures, 810., approximately. Elliptical-shaped figures may be described and marked off by using the scrolls H, proper judgment in all cases being exercised to rotate the disk to the required extent in order to produce correctness in the resultant figures. Where the lines of the figures do not meet or extend the full length, they'may be readily filled out. The line F of the bar D and the slot E are employed as the diameter of the circle formed by the disk, and a radius may be described, using either said line F, the slot E, or the perpendicular d of the right-angled triangle formed by the figure B.

The instrument will be found especially useful for children for drawing geometric and fanciful figures without necessarily employing dividers and rulers, especially as any other regular or irregular devices may be inserted within the rim to produce corresponding figures.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is- I00 1. Aplotter consisting of adisk having openings therein, the sides of which are bounded by right lines of different lengths, forming sides of regular polygons whose centers are coincident with the center of the disk, and

portions of a circle concentric with the circumference of the disk, also having several series of perforations extending radially, substantially as described.

2. A disk having openings forming the outlines of figures B, O, and D, of the shape substantially as described.

3. A disk having a graduated rim, and having openings, substantially as described, form- 

